TRANSPLANT REJECTION ASSOCIATED WITH THE PRESENCE OF HUMAN-LEUKOCYTE ANTIGEN ANTIBODIES DETECTED BY THE FC-GAMMA-R INHIBITION TEST BUT NOT BY THE LYMPHOCYTOTOXICITY TEST

The unselected sera from 869 human leucocyte antigen (HLA) immunized p atients awaiting a kidney transplant were analysed using the complemen t-dependent lymphocytotoxicity test (LCT) with peripheral mononuclear blood cells and the complement-independent immune phagocytosis inhibit ion test (IPI) with monocytes derived from between five and 10 donors. Sera from 659 patients were LCT and IPI negative when tested against this small panel. Seventy-nine patients had HLA immunoglobulin-G (IgG) antibodies, detectable by the IPI only. Sera from 117 patients had co ncordantly positive IPI and LCT reactivity with cells from certain don ors and concordantly negative IPI and LCT reactivity with cells from o ther donors (no isolated IPI and no isolated LCT reactions). Fourteen patients had a mixed type of reactivity. Laboratory findings were inte rpreted along with the transplantation history of the respective patie nts. Group 1 comprised patients for whom negative results were obtaine d in both the LCT and the IPI; group 2 patients who were also LCT nega tive but IPI positive. These two groups showed a significantly differe nt history with respect to the number of irreversible immunological tr ansplant rejections. In group 1, 25.3% of the transplanted kidneys had been rejected whereas in group 2, 56.0% of the kidneys had been rejec ted (p = 5 x 10(-5)). The high incidence of rejections in the group sh owing only IPI reactions was comparable with that of group 4 comprisin g patients with concordant IPI and LCT reactions (59.4%). It is inferr ed from this retrospective study that renal allograft rejection is ass ociated with the development of IPI reactive antibodies which are not detectable by the LCT. The presence of these antibodies prior to trans plantation could be detrimental to the transplanted organ. This being the case, the incidence of transplant failures could be reduced by pre transplant screening using the IPI and by avoiding crossmatch positive donors identified by IPI, especially in patients waiting for a retran splantation.